Closure caps made of plastic material for closing containers, in particular bottles, are largely used in accordance with the state of the art. Many types of embodiment of closure caps are provided with an annular guarantee band which is detachable and torn off from the closure cap when opening the bottle. As long as the annular guarantee band in its intact state is connected to the very closure cap via small links it indicates the original state of the contents of the bottle. Thus, it is guaranteed that the closure cap is fixed on the bottle neck in its original state, preferably screwed there upon.
To this effect the guarantee band, subsequently to the filling and closing of the container, is gripping around and beneath a bead or projection of the bottle neck. When the closure cap is opened the links extending between the side wall of the closure cap and the guarantee band are disrupted by the tensile and the shearing forces. The guarantee band rests on the bottle neck and the closure cap can be unscrewed completely.
At present, polypropylene (PP) is mostly used as a plastic material for the body of the closure cap. The plastic material PP is relatively hard so that the function of the guarantee band is safely ensured. It is almost impossible to lever up the PP-closure cap by means of a tool without visibly damaging it.
Since the sorting means of the filling installation can process only a uniform range of heights of the closure caps without readjustment, the height is fixed uniformly to about 20 mm. The guarantee band rests firmly fixed on the bottle neck and is torn off immediately when attempting to open the bottle.
Beneath the bead or projection which is gripped from beneath of its bottom side by the detachable guarantee band, there is also provided a supporting collar. The bottle is conventionally suspended on this supporting collar while it is being filled and closed thereafter. In this case the bottles are formed particularly of the plastic material PET or PEN. The annular guarantee band of the closure cap, with the here addressed and conventionally used PP-embodiment of the state of the art, ends at a distance of approximately 2 mm above the supporting collar on the bottle neck.
The disadvantage of the known closure cap consists in the fact that it must be manufactured in two parts. Polypropylene would be too hard a material for forming sealing lips which tighten the space existing between the bottle neck and the closure cap. This is particularly critical with PET-bottles which can be afflicted by greater unevennesses and deformations than glass bottles. The softer sealing is made for example of ethylene vinyl acetate (EVA), i.e. two different steps of injection molding as well as a subsequent step of assembling the two-piece closure cap are needed.
In order to avoid this drawback, one-piece closure caps made of polyethylene (PE) have already been proposed: This kind of material is softer than the usual polypropylene and can therefore safely ensure the tightening function by shaping the sealing system, when the closure cap is manufactured in one piece by a sole step of injection molding.
On the other hand, when applying the softer PE-material, there is the risk that the guarantee band can be detached by a fraud and that integrity is feigned. Therefore, the one-piece plastic closure cap made of PE has not made its way until now because of the problem of ensuring guarantee.
For this reason there is a need for a one-piece plastic closure cap, the guarantee function of which ensures more security than before.
From the U.S. Pat. No. 4,592,476 there is known a plastic closure cap in accordance with the preliminary part of patent claim 1, wherein the removable guarantee band is extended in the direction of the central axis of the closure cap. According to the U.S. patent specification the guarantee band extends up to the supporting collar of the container when the closure cap sits on the opening of the container and the guarantee-band grips beneath the bead or projection on the bottle neck.
From the European patent application EP 536 082 there is known a closure cap which is made in one piece together with the guarantee band by injection molding. Connecting elements are disposed between the closure cap and the guarantee band. On the bottom of the cap cover there is provided an inner sealing.
From the European patent application EP 316 167 there is known the combination of a bottle and a closure cap. The bottle consists of polyethyleneter ephtalate (PET). The closure cap is formed of a thermoplastic resin like polyolephine for example. The closure cap has an annular shoulder 10 which rests on the upper and outer surface of the bottle neck. In addition, the closure cap has an annular rib 13 which (inwardly from the shoulder 10) rests elastically on the inner surface of the bottle neck.
From the international application WO 93/24386 there is known a closure cap for multi-way-PET-bottles provided with a cap wall having an inner thread, a front wall closing the cap wall, and a guarantee band connecting to the cap wall. The front wall has a circular inner sealing spaced apart from the cap wall and projecting downwardly to the open end of the cap, with the outer diameter of the sealing tapering in the region of the free end towards the latter. For gas tight use the closure cap is configured such that the inner sealing has a bead in the region of the free end which is directed to the cap wall and such that the bead encloses the region which tapers in respect of its outer diameter.
Finally, a closure cap for releasable closing of a container is known from the international application WO96/02430 which comprises a cap body that corresponds to the container. The cap body and a seal cooperate with the upper edge of the container for closing the container. The closure cap comprises at least one shoulder formed on the cap body which shoulder extends opposite to the upper edge and cooperates in the closing phase with the sealing.
In addition to reliably ensuring the guarantee function and the sealing function it is desirable not to impose particular requirements on behalf of such closure caps as to tolerances. It is also desirable that the closure cap can be manufactured, i.e. formed in and deformed from a mould in few steps and that it is capable for being recycled after use.
The problem to be solved by the invention consists therefore in the provision of a one-piece plastic enclosure, in particular made of PE-material, which can be placed on a filled container without satisfying particular tolerance requirements while simultaneously satisfying the additional, in part contradictory requirements, namely to be manufactured in a few steps and to be apt for recycling after use, while ensuring the guarantee function and the sealing function.
In accordance with the present combinational invention, the solution consists in the provision of a closure cap which has an extended closure guarantee band and an extended inner seal, i.e. a sealing which projects about and along the edge of the container neck into the opening, which cap is characterized in combination by:
a funnel- or bell-shaped prolongation at the free end of the guarantee band,
a wedge-shaped outer surface on the extended inner seal, and
an average standard solidity of the plastic material of the one-piece closure cap (in particular as to the PE-material) such that
the funnel- or bell-shaped guarantee prolongation sits on the supporting collar of the container in a non-undergrippable manner and
the wedge-shaped outer surface of the inner seal rests on the container neck in a pressing manner.
Because of the funnel-shaped extension on the guarantee band and the wedge- or funnel-shaped outer surface on the inner sealing, the plastic closure can be placed on a filled container without particular tolerance requirements. Because of forming the cap in one piece, the plastic closure can be formed and taken out (deformed from) of the mould in a few steps. Because of the same feature (only one type of plastic material), the plastic closure cap allows for being recycled after use. The guarantee function for the closed container is reliably ensured by the fact that the funnel- or bell-shaped prolongation of the guarantee band sits on the supporting collar of the filled container. The tightening function for the closed container is reliably ensured by the fact that the wedge- or funnel-shaped outer surface of the inner seal rests on the container neck. The plastic material has, when used, a solidity which is hard enough for complying with the funnel-shaped guarantee band and at the same time soft enough for complying with the extended wedge-shaped inner sealing. The undercuts at the guarantee band and at the inner sealing can be removed from the mould as long as the warm plastic material has not yet reached its full strength or solidity needed for use.
Further features of the invention are characterized in the sub-claims. According to patent claim 4 the guarantee band can be longer in the direction of the central axis of the closure cap than the usually applied 20 mm. In particular, a total height of 23.5 mm is suited for closing PET-bottles being in use nowadays. In using these lengths the guarantee band extends down to the supporting collar and is tightly pressed upon it. The lower end of the guarantee band can sit thereupon similar to a bell so that it cannot be gripped from below, and it offers sufficient security too, although the relatively smooth PE-material is used.
A one-piece structure of the entire closure cap is obtained (patent claim 2). The preferred material polyethylene (PE) used under these circumstances is characterized in patent claim 3.
It is of importance to adjust all of the functions of the closure cap to the shape and to the material of the container to be closed. In the preferred example or embodiment, the container is a bottle (patent claim 6) which is provided with a screw-type cap. The bottle is made preferably of plastic material (patent claim 7). At present, PET-bottles, but also PEN-bottles are conventionally used and wide-spread (patent claim 8), with the claimed plastic closure caps being particularly well suited. Nonetheless, the preferred examples of embodiment concerning the structure and the use of the closure caps are not meant to restrict the invention formulated in the patent claim 1.
In the sub-claims 9 to 23 or dependent claims, a sealing system xe2x80x9caxe2x80x9d combined with the extended guarantee band is claimed. In the sub-claims 24 to 35, a sealing system xe2x80x9cbxe2x80x9d in combination with the extended guarantee band is the object. The sub-claim 36 relates to a scaly structure at the rear side of a thin, wedge-shaped sealing lip.